It may burn more calories, but my feet/legs would be angry about all that standing. :o)
I have been known to set a timer (15 to 60 minutes, depending on how ambitious I am feeling!) so that I have to get up every so often and do something else. Sometimes I use this system to get things done like housework, or I just go up and down the stairs a couple of times during each break. It does seem that anything past 40 minutes or so leaves me feeling like a lump, as you say.
If you really want to gamify it, you could set a die next to your computer and roll it to decide what exercise/chore/anything you will do on your breaks. =)